I'm having trouble passing a pointer to AngelScript

I'm working on a game engine, using AngelScript. I have registered my entity class to AngleScript (there is no constructor on purpose, I don't want users to be able to declare new entities):

r = engine->RegisterObjectType("Entity", 0, asOBJ_REF); assert(r >= 0);
r = engine->RegisterObjectBehaviour("Entity", asBEHAVE_ADDREF, "void f()", asMETHOD(Entity, AddRef), asCALL_THISCALL); assert(r >= 0);
r = engine->RegisterObjectBehaviour("Entity", asBEHAVE_RELEASE, "void f()", asMETHOD(Entity, ReleaseRef), asCALL_THISCALL); assert(r >= 0);
r = engine->RegisterObjectMethod("Entity", "Transform& getTransform()", asMETHOD(Entity, get<Transform>), asCALL_THISCALL); assert(r >= 0);

I've also registered my Transform component:

r = engine->RegisterObjectType("Transform", sizeof(Transform), asOBJ_VALUE | asOBJ_POD | asOBJ_APP_CLASS_CAK …